JPS59156753A - Reinforcing method of screen printing pattern - Google Patents

Abstract

PURPOSE:To obtain sufficient anti-print pigment provided with a high performability inherent to a single liquid method and with an ample thickness of film without spoiling a sharpness of image produced by phototypesetting. CONSTITUTION:A surface of screen printing pattern is covered with chlorinated polyolefic solution and dried. The chlorinated polyolefin to be employed should be of weight average molecular weight of 500,000-100,000, preferably <10,000- 50,000. If the weight average molecular weight is as low as 5,000 max., then poor film formation would cause anti-printing property and if it is as high as 100,000min., then solubility in solvent would be invited, causing poor operatability of film to the printing pattern. When the chlorinated polyolefic solution has its viscosity within a range of 10-1,000Cp, then it can be employed with high standard at operatability for covering a screen printing pattern. This range would be preferably within a range of 100-500cp.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to screen printing.

More specifically, the present invention relates to a method for reinforcing a screen printing board.

(Prior art) Screen printing plates are manufactured by photolithography using a water-soluble photosensitizer whose main component is vinyl acetate emulsion or polyvinyl alcohol, mainly from the viewpoint of workability and fire prevention. The plate or image naturally has the disadvantage of being sensitive to printing pastes that use water as a solvent, so it is generally painted with a two-component urethane paint with the main purpose of improving printing resistance to compensate for this disadvantage. It has been reinforced. However, this two-component urethane paint has a short pot life after mixing the two-component paints, making it easy to waste paint, and incyanate, one of the components of the two-component urethane paint, is easily decomposed by moisture, and is difficult to use during the rainy season. However, in order to obtain sufficient printing resistance, it is necessary to form a two-component urethane coating with a thickness of 20 to 30 μm on the surface of the screen printing plate. However, it has disadvantages such as impairing the sharpness that photoengraved images originally have and making them expensive.

Therefore, in the screen printing plate industry, there is a strong desire to develop a reinforcing agent that is one-component, easy to work with, and has sufficient printing resistance with a coating thickness that does not impair the sharpness of photolithographic images. .

(Objective of the Invention) The object of the present invention is to develop a reinforcing agent that is liquid-based, has good workability, and provides sufficient printing resistance with a coating thickness that does not impede the sharpness of photolithographic images. It is to be.

(Structure of the invention) As a result of intensive research for the above purpose, the inventors have
The present inventors have discovered that a chlorinated polyolefin film has good adhesion to photolithographic images, and also has excellent water resistance and printing resistance, and has completed the present invention.

That is, the present invention is a method for reinforcing a screen printing plate, which is characterized in that the surface of the screen printing plate is coated with a chlorinated polyolefin solution having a chlorine content of 5 to 60% by weight and then dried.

The components of the present invention will be individually explained in detail below.

(Chlorinated polyolefin) The chlorinated polyolefin used in the present invention can be easily produced by an aqueous suspension method in which polyolefin is dispersed in water and chlorinated, or a solvent method in which polyolefin is dispersed in an organic solvent and chlorinated. can be manufactured. In the present invention, polyolefin generally refers to polyolefin.

Used in the present invention. The chlorinated polyolefin has a weight average molecular weight of 5,000 to 100,000, preferably 10
The chlorine content is preferably 5 to 60% by weight, preferably 10 to 50% by weight. 5. Low weight average molecular weight. (100
If it is less than 100%, the film forming ability will be poor and the printing resistance will be reduced, and the weight average molecular weight will be too high. If it is OO or more, the solubility in the solvent is poor, and the workability of coating the printing plate is reduced. In addition, if the chlorine content is less than 5% by weight, it has poor solubility and it is difficult to form a homogeneous solution.If the chlorine content exceeds 60% by weight, the solubility is good, but the film is hard and brittle, making it impractical. Does not have certain printing resistance. In short, it is desirable to select the weight average molecular weight and chlorine content in consideration of both printing resistance and coating workability.

(Solvent) The solvent used in the chlorinated polyolefin solution of the present invention may be a single solvent or a mixture of two or more solvents, taking into account the solubility of the chlorinated polyolefin, ease of coating on the screen printing plate, drying performance, etc. should be selected as In general, aromatic hydrocarbon or chlorinated hydrocarbon solvents are suitable, such as toluene, xylene, benzene, solvent naphtha, 1,1.1-)lichloroethane, carbon tetrachloride, trichloroethylene, perchloroethylene, chloroform. etc. can be mentioned. In addition, dimethylsulfone, ethyl acetate, ethylene glycol monoethyl acetate, methyl ethyl ketone, cyclohexanone, dimethylformamide, tetrahydrofuran, etc. can also be used.

(Viscosity of the melt) The viscosity of the chlorinated polyolefin solution is 10~LOO
When the OcP is within the range, it can be used to coat the surface of a screen printing plate with good workability.

It is preferably in the range of Vth 100 to 500 cP.

If it exceeds 1.000 cP, stringing of the chlorinated polyolefin occurs when coating the surface, making it impossible to coat the surface with a uniform thickness. Furthermore, if the viscosity is less than 10 cP, sufficient strength to provide printing resistance cannot be obtained.

(Coating method and drying method) In order to coat and reinforce the surface of a screen printing plate using the polyolefin solution of the present invention, coating can be performed by conventionally known methods such as brush coating, spraying, and dipping. can. After the entire surface has been covered, unnecessary portions of the polyolefin film can be selectively deposited on the screen mask by blowing compressed air or, conversely, by sucking up the polyolefin film under reduced pressure. Thereafter, a reinforcing film is formed by drying at a temperature of 60° C. or lower while ensuring that the image area does not come into contact with anything else.

(Auxiliary materials) The chlorinated polyolefin solution used in the present invention can be used by blending other resins that are compatible with it, but the amount of blending depends on the adhesiveness and resistance of the chlorinated polyolefin. The blending should be within a range that can maintain printing properties, and the purpose of blending should be to improve workability against degradation. Examples of resins that can be blended with chlorinated polyolefins include chloroprene rubber, ethylene-vinyl acetate copolymer, polyvinyl chloride, chlorinated rubber, and vinyl chloride-vinyl acetate copolymer. It is desirable that the amount coefficient is 1 oM or less.

Among these resins, for example, polyvinyl chloride and chlorinated rubber are effective in lowering the solution viscosity and are advantageous in preventing stringiness during coating. Also, chloroprene rubber, ethylene-vinyl acetate copolymer,
If a vinyl chloride-vinyl acetate copolymer is used, the adhesion to the screen printing board will be improved. Therefore, it is desirable to blend resins appropriately depending on the intended use, taking these properties into account.

It should be noted that stabilizers, fillers, pigments, plasticizers, crosslinking agents, etc. may be appropriately added to the chlorinated polyethylene solution used in the present invention, but these may be added in such a way that they do not impair the purpose or advantage of the present invention. Needless to say, you have to choose.

(Examples) Examples are shown below to make the present invention easier to understand, but the following examples do not limit the present invention.

Example 1 Chlorinated polypropylene solution Higashi Super Chron 803 M
” (Product name, Sanyo Kokusaku) Manufactured by Tsuruzo Co., Ltd., chlorine content 3
0±]wt%, solid content 30%) Swasol'1 = 15oo (trade name, manufactured by Maruzen Sekiyu Co., Ltd.) to 10
After diluting the diluted 2 times and applying it with a brush onto an image photoengraved with a vinyl acetate emulsion and polyvinyl alcohol based photosensitizer on a 120-mesh Tetron screen, the area other than the image was removed with compressed air. , 40
The screen printing plate was reinforced by drying at ℃ for 1 hour.

After immersing this reinforced screen printing board in a 5-coefficient soda aqueous solution and a 5-thiformic acid aqueous solution for 1 hour each,
After rubbing with a cloth 50 times, the reinforced image showed no abnormalities, and was confirmed to repel water well and have sufficient printing resistance.

Example 2 Chlorinated polypropylene solution - Super Chron 772L"
(Product name, Sanyo Kokusaku Pulp Co., Ltd., chlorine content: 13-
1: For single layer use: Toluene solution with a solid content of 20 parts was diluted 5 times with NRUBETSUN" 150 (trade name, manufactured by Esso Standard Oil Co., Ltd.), and this was used in the same manner as in Example 1 to reinforce the screen printing board. However, when tested, it was found to have sufficient printing resistance.

Example 3 Weight average molecule i50,000. Polyethylene with a melting point of 129°C was chlorinated by a solvent method to obtain chlorinated polyethylene ff: with a chlorine content of 50%. Dissolve this in a mixed solvent of 30 parts by weight of xylene and 70 parts by weight of trichlorethylene,
A 5% by weight solution was prepared. When this liquid was used to reinforce a screen printing board in the same manner as in Example 1 and tested, it was found to have sufficient printing resistance.

Comparative Example 1 [Element (t['lJ Propylene 1 Super Chron 106T
” (Product name, manufactured by Sanyo Kokusaku Pulp Co., Ltd., chlorine content 6
6% or more) was dissolved in a mixed solvent of 30% by weight of xylene and 70% by weight of trichlorethylene to form a 5% by weight solution.

When a screen printing plate was reinforced using this in the same manner as in Example 1 and tested, sufficient printing resistance could not be obtained because the adhesion of the reinforcing film to the plate-making image was weak and the casing was hard and brittle. There wasn't.

(Effects of the Invention) The method for reinforcing a screen printing board using the chlorinated polyolefin solution of the present invention is different from the conventional reinforcing method using a two-component urethane paint: - Since it is liquid-based, the trouble of preparing the reinforcing solution can be saved; It is unaffected by moisture, has excellent storage stability, does not go to waste, has excellent adhesion to printing plate images, and can form a relatively thin reinforcing film with excellent water and chemical resistance, resulting in sharp printing resistance. It has the advantage of being able to produce screen printing plates with good properties, and has extremely high industrial value.

Claims (2)

[Claims] (1) A method for reinforcing a screen printing board, which comprises coating the surface of the screen printing board with a chlorinated polyolefin solution and drying it. (2) Chlorine content of chlorinated polyolefin is 5 to 60
% by weight. The method for reinforcing a screen printing board according to claim 1.